This study was undertaken to examine gender differences in the perception of social constraints against smoking and to explore the role of other sociodemographic and smoking factors that influence the perception of social pressure. Baseline data from the 20 U.S. sites in the National Cancer Institute's Community Intervention Trial for Smoking Cessation (COMMIT) were analyzed. We found that women were less likely than men to be heavy smokers and to report that smoking had affected their health, but more likely to report behavior indicating physiological addition (timing of first cigarette). At all smoking levels, women were about twice as likely as men to report feeling pressure to quit, after adjusting for education, income, ethnic group, age, and other factors. The source of pressure, however, was different: more women report pressure from their children, whereas more men report pressure from friends and coworkers. Women were equally likely as men to make quit attempts, after adjusting for other factors, but were less likely to remain abstinent for at least 10 days. Women, regardless of education, ethnicity, and age, reported a greater tendency to ask permission before smoking in non-restricted public places. College-educated men were less likely than men without college education to smoke without asking in non-restricted places, but education did not influence whether women asked permission. For both sexes, smoking level and nicotine dependence were significant predictors of lighting up without asking in public places, after adjustment for other variables. We discuss these findings and their implications for the gender gap in smoking cessation and women's conflicting pressures to stop/continue smoking. Tobacco control efforts are discussed within the context of gender differences in social norms, roles, socialization, and communication cultures.